Bid Request

A bid request is the message an exchange sends to buyers when an impression becomes available. It describes the opportunity: the app or site, the placement and format, the device and operating system, connection type, approximate location and any user signals the publisher is allowed to share. Most bid requests follow the OpenRTB standard.

A DSP has milliseconds to read the bid request, decide whether the impression is worth buying for any active campaign, set a price and return a creative. The richness and accuracy of bid request data shape how well this works. Mismatched app information or suspicious device signals in a bid request are also common indicators of invalid traffic, which is why pre-bid filtering inspects bid requests before any money is spent.

Understanding bid requests also explains why some impressions cost more than others: richer, more trustworthy signals let buyers bid with confidence, and confident buyers pay higher prices.